My Cummins lost its sound

[Cody A Souder]

I have a 1993 club can 5 speed intercooled 4x4 Cummins dually. It has 250k on it and I've had my truck a little over 3 years. About a year and a half ago I had the injection pump professionally rebuilt and maxed out with a THD fuel pin, 3800 governor spring, and a new Bosch fss. I also installed new 5x12 vco injectors, a new hvlp lift pump, and a diamond eye 4 inch turbo back straight pipe exhaust. The rest of the truck is stock. After doing this work there truck ran amazing. It woke it right up. About 800 miles after doing this work I accidentally got it stuck in some mud in my yard. In the process of trying to get it out I was working it kind of hard and all of a sudden I could hear it die down. It smoked less, the idle was quieter and lower. When I got it out I drove it to town and I could barely hear it running as I was driving it and it would stall if I let it idle down. I pulled the pump and injectors and sent them back to have them tested and they tested good. I replaced the hvlp lift pump with a brand new one and im getting 18 to 20psi. I have a boost gauge and it spikes about 28 to 30psi. I still drive the truck and it starts everytime but it just sounds dull and muffled. The exhaust doesn't even echo off walls and buildings, I can barely hear it with the windows down. It smokes less and is a lighter color and when I shut it down sometimes it diesels for a second or two before it stops. I also noticed a lack of torque and low end power and it's much when towing. Any help would be greatly appreciated to help me diagnose this

 

[dieselshadow]

Did you check your timing?

 

[Cody A Souder]

Yes pump timing is advanced toward the head and gear timing hasn't changed

 

[sdeeter19555]

Did you shear the woodruff key?

 

[dieselshadow]

This sounds like timing, hence why I asked.

 

[Cody A Souder]

Did you shear the woodruff key?

It looked fine when I pulled the pump to have it tested

 

[Cody A Souder]

This sounds like timing, hence why I asked.

I thought the same thing but I pulled the timing cover to look everything over when I pulled the pump and everything looked normal. Nothing had moved or skipped

 

[dieselshadow]

Doesn’t the VE pump have slots in the mounting flange for timing adjustments? You can’t really just slap an old school pump on and expect the best optimization. It has to be checked.

 

[Cody A Souder]

Doesn’t the VE pump have slots in the mounting flange for timing adjustments? You can’t really just slap an old school pump on and expect the best optimization. It has to be checked.

When I had the pump rebuilt it was calibrated and he told me where the best place to put it for pump timing would be. This happened after installing the rebuilt pump was on and timing for a couple months. The pump flanges are slotted and I have it about 1/4 inch advanced toward the head

 

[dieselshadow]

Ok, you need to check the timing. At least consult with your pump builder. You’re describing timing slip to a T. Just sayin’.

 

[Cody A Souder]

Ok, you need to check the timing. At least consult with your pump builder. You’re describing timing slip to a T. Just sayin’.

Do you mean internal pump timing? I double checked my timing gears and my pump placement and they are right where they were from the beginning

 

[dieselshadow]

That’s not how you check timing. It usually takes a dial indicator and a TDC indicator, some special tools. I’m not a VE expert and haven’t timed one personally, so I can’t say what it takes tool wise. But I can say you can’t just bolt a mechanical pump up and call it good. That kind of blind faith doesn’t mean it’s accurate. I know from the P7100 pumps you need dial indicators and a properly setup TDC gauge to set timing correctly. It’s not hard, but it’s a lot more time consuming than a gasser.

 

[Cody A Souder]

That’s not how you check timing. It usually takes a dial indicator and a TDC indicator, some special tools. I’m not a VE expert and haven’t timed one personally, so I can’t say what it takes tool wise. But I can say you can’t just bolt a mechanical pump up and call it good. That kind of blind faith doesn’t mean it’s accurate. I know from the P7100 pumps you need dial indicators and a properly setup TDC gauge to set timing correctly. It’s not hard, but it’s a lot more time consuming than a gasser.

Im not trying to sound like a dick because I do appreciate the help. But basically I just got lucky when I put the pump on in the first place and it slipped from rpm and engine load?

 

[dieselshadow]

That’s what you’re describing. Doesn’t mean that’s what’s up though. We are diagnosing your problem over the Internet with not much info. So I hope I’m not coming across wrong, I’m just telling you what I think based on your description. I’m just a fella on the Internet telling you what I think it is based on what I’ve read. Take it for what it is.

I’d call your pump builder and ask their advice. They’ll likely lead you down the same path.

 

[Cody A Souder]

When I first started having the issue he was the first one I talked to. I explained to him what was going on and he recommended getting my injectors tested so I talked to THD about getting my injectors tested and he told me to get my pump tested. So I told both of them the issue and sent my pump and injectors out to have them tested where I got them. The injectors tested fine and so did the pump. He locked it at tdc. I had it at tdc before I took it apart so I put the pump back in, primed it, advanced timing by rotating the pump.

 

[Jihn]

I know I'm going to get ripped apart for this comment but here goes, did you change "all" of your fuel filters, sounds like what had happened to me years ago on a Mack I used to drive, it happened more than once(while you were "working" the truck to get it out it tends to stir everything in the fuel tank, and the lift pump picks it up and sends you where).
Just a thought.

Jihn

 

[Cody A Souder]

I know I'm going to get ripped apart for this comment but here goes, did you change "all" of your fuel filters, sounds like what had happened to me years ago on a Mack I used to drive, it happened more than once(while you were "working" the truck to get it out it tends to stir everything in the fuel tank, and the lift pump picks it up and sends you where).
Just a thought.

Jihn

I changed my fuel / water separator filter. Haven't pulled the sending unit. I did replace the lift pump

 

[NIsaacs]

Is there any chance gas was put in the tank or alcohol based additive?